Frame Relay

Chapter 14

Establishing a Frame  Relay PVC Connection © 1999, Cisco Systems, Inc. 

14­1

© 1999, Cisco Systems, Inc. 

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Objectives Upon completion of this chapter, you will be able to perform the following tasks: • Determine how Frame Relay operates • Configure Frame Relay • Configure Frame Relay subinterfaces • Verify Frame Relay operation

© 1999, Cisco Systems, Inc. 

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Frame Relay Overview DCE or  Frame Relay Switch CSU/DSU

Frame Relay works here.

• Virtual circuits make connections • Connection­oriented service © 1999, Cisco Systems, Inc. 

www.cisco.com

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Frame Relay Stack OSI Reference Model

Frame Relay

Application Presentation Session Transport

© 1999, Cisco Systems, Inc. 

Network

IP/IPX/AppleTalk, etc.

Data Link

Frame Relay

Physical

EIA/TIA­232,  EIA/TIA­449, V.35,  X.21, EIA/TIA­530

www.cisco.com

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Frame Relay Terminology DLCI: 100

PVC DLCI: 200

LMI

100=Active 400=Active

DLCI: 400

Local Access Loop=64 kbps

Local Access Loop=T1 PVC DLCI: 500

© 1999, Cisco Systems, Inc. 

Local Access Loop=64 kbps

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Frame Relay  Address Mapping DLCI: 500

PVC

10.1.1.1

CSU/DSU

Inverse ARP or Frame Relay map Frame DLCI (500) Relay

IP (10.1.1.1)

• Get locally significant DLCIs from provider  • Map your network addresses to DLCIs © 1999, Cisco Systems, Inc. 

www.cisco.com

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Frame Relay Signaling DLCI: 500

x

PVC

10.1.1.1

CSU/DSU

LMI

500=Active 400=Inactive

DLCI: 400

PVC

Keepalive

Cisco supports three LMI standards: • Cisco • ANSI T1.617 Annex D • ITU­T Q.933 Annex A

© 1999, Cisco Systems, Inc. 

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Frame Relay Inverse ARP and  LMI Operation 1 DLCI=100

Frame Relay Cloud

172.168.5.5

© 1999, Cisco Systems, Inc. 

DLCI=400 172.168.5.7

www.cisco.com

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Frame Relay Inverse ARP and  LMI Operation 1 DLCI=100

Frame Relay Cloud

172.168.5.5

2

© 1999, Cisco Systems, Inc. 

DLCI=400 172.168.5.7

Status Inquiry

Status Inquiry

www.cisco.com

2

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Frame Relay Inverse ARP and  LMI Operation 1

Frame Relay Cloud

DLCI=100

DLCI=400

172.168.5.5

2

Status Inquiry

Local DLCI 100=Active

© 1999, Cisco Systems, Inc. 

172.168.5.7 Status Inquiry

3

www.cisco.com

34

2

Local DLCI 400=Active

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Frame Relay Inverse ARP and  LMI Operation 1

Frame Relay Cloud

DLCI=100

DLCI=400

172.168.5.5

172.168.5.7

Status Inquiry

2

Local DLCI 100=Active

4

© 1999, Cisco Systems, Inc. 

Status Inquiry

3

34

2

Local DLCI 400=Active

Hello, I am 172.168.5.5.

www.cisco.com

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Frame Relay Inverse ARP and  LMI Operation (cont.) Frame Relay Cloud

DLCI=100

DLCI=400 172.168.5.7

172.168.5.5

Frame Relay Map 172.168.5.5  DLCI  400  Active Hello, I am 172.168.5.7.

5

© 1999, Cisco Systems, Inc. 

5 4

Frame Relay Map 172.168.5.7  DLCI  100  Active

www.cisco.com

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Frame Relay Inverse ARP and  LMI Operation (cont.) Frame Relay Cloud

DLCI=100

DLCI=400 172.168.5.7

172.168.5.5

Frame Relay Map 172.168.5.5  DLCI  400  Active Hello, I am 172.168.5.7.

5 6

© 1999, Cisco Systems, Inc. 

5 4

Frame Relay Map 172.168.5.7  DLCI  100  Active Hello, I am 172.168.5.5.

www.cisco.com

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Frame Relay Inverse ARP and  LMI Operation (cont.) Frame Relay Cloud

DLCI=100

DLCI=400 172.168.5.7

172.168.5.5

Frame Relay Map 172.168.5.5  DLCI  400  Active Hello, I am 172.168.5.7.

5 6 7 © 1999, Cisco Systems, Inc. 

5 4

Frame Relay Map 172.168.5.7  DLCI  100  Active Hello, I am 172.168.5.5. Keepalives

Keepalives

www.cisco.com

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Configuring Basic Frame  Relay Rel. 11.2 Router

Rel. 10.3 Router Branch

HQ

interface Serial1 ip address 10.16.0.1 255.255.255.0   encapsulation frame-relay bandwidth 64

© 1999, Cisco Systems, Inc. 

interface Serial1 ip address 10.16.0.2 255.255.255.0 encapsulation frame-relay bandwidth 64 frame-relay lmi-type ansi

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Configuring Basic Frame  Relay (cont.) Rel. 11.2 Router

Rel. 10.3 Router Branch

HQ

interface Serial1 interface Serial1 ip address 10.16.0.2 255.255.255.0 ip address 10.16.0.1 255.255.255.0 encapsulation frame-relay   encapsulation frame-relay bandwidth 64 bandwidth 64 frame-relay lmi-type ansi

Inverse ARP • Enabled by default • Does not appear in configuration output © 1999, Cisco Systems, Inc. 

www.cisco.com

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Configuring a Static Frame  Relay Map DLCI=110 IP address=10.16.0.1/24 

p1r1 HQ

Branch

DLCI=100 IP address=10.16.0.2/24 

interface Serial1 ip address 10.16.0.1 255.255.255.0 encapsulation frame-relay bandwidth 64 frame-relay map ip 10.16.0.2 110 broadcast

© 1999, Cisco Systems, Inc. 

www.cisco.com

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Verifying Frame Relay  Operation Router#show interface s0 Serial0 is up, line protocol is up Hardware is HD64570 Internet address is 10.140.1.2/24 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255 Encapsulation FRAME-RELAY, loopback not set, keepalive set (10 sec) LMI enq sent 19, LMI stat recvd 20, LMI upd recvd 0, DTE LMI up LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0 LMI DLCI 1023 LMI type is CISCO frame relay DTE FR SVC disabled, LAPF state down Broadcast queue 0/64, broadcasts sent/dropped 8/0, interface broadcasts 5 Last input 00:00:02, output 00:00:02, output hang never Last clearing of "show interface" counters never Queueing strategy: fifo Output queue 0/40, 0 drops; input queue 0/75, 0 drops

Displays line, protocol, DLCI, and LMI information © 1999, Cisco Systems, Inc. 

www.cisco.com

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Verifying Frame Relay  Operation (cont.)

ame-relay lmi

for interface Serial0 (Frame Relay DTE) LMI TYPE = CISCO bered info 0 Invalid Prot Disc 0 Call Ref 0 Invalid Msg Type 0 s Message 0 Invalid Lock Shift 0 mation ID 0 Invalid Report IE Len 0 t Request 0 Invalid Keep IE Len 0 q. Sent 113100 Num Status msgs Rcvd 113100 atus Rcvd 0 Num Status Timeouts 0

Displays LMI information

© 1999, Cisco Systems, Inc. 

www.cisco.com

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Verifying Frame Relay  Operation (cont.) Router#show frame-relay pvc 100 PVC Statistics for interface Serial0 (Frame Relay DTE) DLCI = 100, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0 input pkts 28 output pkts 10 in bytes 8398 out bytes 1198 dropped pkts 0 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 out bcast pkts 10 out bcast bytes 1198 pvc create time 00:03:46, last time pvc status changed 00:03:47

Displays PVC traffic statistics

© 1999, Cisco Systems, Inc. 

www.cisco.com

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Verifying Frame Relay  Operation (cont.)

how frame-relay map (up): ip 10.140.1.1 dlci 100(0x64,0x1840), dynamic, broadcast,, status defined, active

Displays the route maps, either static or dynamic

© 1999, Cisco Systems, Inc. 

www.cisco.com

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Verifying Frame Relay  Operation (cont.)

rame-relay map ip 10.140.1.1 dlci 100(0x64,0x1840), dynamic, broadcast,, status defined, active frame-relay-inarp me map

Clears dynamically created Frame Relay maps

© 1999, Cisco Systems, Inc. 

www.cisco.com

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Verifying Frame Relay  Operation (cont.)

debug Frame lmi elay LMI debugging is on ing all Frame Relay LMI data

erial0(out): StEnq, myseq 140, yourseen 139, DTE up atagramstart = 0xE008EC, datagramsize = 13 R encap = 0xFCF10309 0 75 01 01 01 03 02 8C 8B

erial0(in): Status, myseq 140 T IE 1, length 1, type 1 A IE 3, length 2, yourseq 140, myseq 140 erial0(out): StEnq, myseq 141, yourseen 140, DTE up atagramstart = 0xE008EC, datagramsize = 13 R encap = 0xFCF10309 0 75 01 01 01 03 02 8D 8C

erial0(in): Status, myseq 142 T IE 1, length 1, type 0 A IE 3, length 2, yourseq 142, myseq 142 VC IE 0x7 , length 0x6 , dlci 100, status 0x2 , bw 0

Displays LMI debug information © 1999, Cisco Systems, Inc. 

www.cisco.com

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Selecting a Frame Relay  Topology

Full Mesh

Partial Mesh Star (Hub and Spoke)

Frame Relay default: nonbroadcast, multiaccess (NMBA) © 1999, Cisco Systems, Inc. 

www.cisco.com

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Reachability Issues with  Routing Updates Routing Update AA

B

B

1 2

C

C

3

D

Problem:

Broadcast traffic must be replicated for  each active connection

© 1999, Cisco Systems, Inc. 

www.cisco.com

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Resolving Reachability Issues Logical Interface  S0.1 S0.2 S0.3

S0

Physical Interface Subnet A Subnet B

Subnet C

Solution:

• Split horizon can cause problems in NBMA environments • Subinterfaces can resolve split horizon issues • A single physical interface simulates multiple logical interfaces

© 1999, Cisco Systems, Inc. 

www.cisco.com

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Configuring Subinterfaces • Point­to­Point

– Subinterfaces act as leased line  – Each point­to­point subinterface requires its own  subnet  – Applicable to hub and spoke topologies 

• Multipoint

– Subinterfaces act as NBMA network so they do not  resolve the split horizon issue – Can save address space because uses single subnet – Applicable to partial­mesh and full­mesh topology

© 1999, Cisco Systems, Inc. 

www.cisco.com

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Configuring Point­to­Point  Subinterfaces 10.17.0.1 s0.2 A

DL s0.3 C 10.18.0.1 I=1

interface Serial0 no ip address encapsulation frame-relay ! interface Serial0.2 point-to-point ip address 10.17.0.1 255.255.255.0  bandwidth 64 frame-relay interface-dlci 110 ! interface Serial0.3 point-to-point ip address 10.18.0.1 255.255.255.0  bandwidth 64 frame-relay interface-dlci 120 !

© 1999, Cisco Systems, Inc. 

DLCI=110

10.17.0.2 B

20

10.18.0.2

www.cisco.com

C

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Multipoint Subinterfaces  Configuration Example s2.2=10.17.0.1/24 RTR1

120 = I C L D DLCI=130 DLCI=

s2.1=10.17.0.2/24 RTR3

s2.1=10.17.0.3/24

140

interface Serial2 no ip address encapsulation frame-relay ! interface Serial2.2 multipoint ip address 10.17.0.1 255.255.255.0  bandwidth 64 frame-relay map ip 10.17.0.2 120 broadcast frame-relay map ip 10.17.0.3 130 broadcast frame-relay map ip 10.17.0.4 140 broadcast

© 1999, Cisco Systems, Inc. 

B

www.cisco.com

RTR4

s2.1=10.17.0.4/24

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Visual Objective wg_pc_a 10.2.2.12 e0/1

e0/2

e0

wg_ro_a

10.2.2.3

s0 10.140.1.2/24

wg_sw_a 10.2.2.11 

PPP with CHAP wg_pc_l 10.13.13.12 e0/1

wg_ro_l e0/2

e0 10.13.13.3 

wg_sw_l 10.13.13.11 

PPP with CHAP s0 10.140.12.2/24

FR

pod A B C D E F G H I J K L

ro’s s0 10.140.1.2 10.140.2.2 10.140.3.2 10.140.4.2 10.140.5.2 10.140.6.2 10.140.7.2 10.140.8.2 10.140.9.2 10.140.10.2 10.140.11.2 10.140.12.2

... fa0/24 core_ server 10.1.1.1 © 1999, Cisco Systems, Inc. 

  

core_sw_a 10.1.1.2

fa0/23

s2/7.x 10.140.1.1/24 … 10.140.12.1/24

fa0/0 core_ro 10.1.1.3 www.cisco.com

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Summary After completing this chapter, you should be able to perform the following tasks: • Configure a Frame Relay PVC on a serial  interface • Configure Frame Relay subinterfaces • Verify Frame Relay operation with show  commands

© 1999, Cisco Systems, Inc. 

www.cisco.com

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Review Questions 1.  What is a DLCI? 2. What are two methods to map a network  layer address to a DLCI on a Cisco  router? 3. What are the advantages of configuring  Frame Relay subinterfaces?

© 1999, Cisco Systems, Inc. 

www.cisco.com

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Blank for pagination

© 1999, Cisco Systems, Inc. 

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